Antenna array



Oct. 28, 1947. A A. G. KANDOIAN 2,429,629

ANTENNA ARRAY Filed DSC. 16, 1942 "QgQozZ-y Q ;IX M7 l l l Ns )EE-1g J1 7mm/Lianne I l 15142 110 2,34 164 "2015 X/Jo f2/1] jl i 35,42 M

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` ATIoRNEY Patente-d Oct. 28, 1947 Armig @.andoiam-ew York; 'i

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This invention relates-to antenna arrays and more. particularly to antenna. arraysponstrncted to provide different` energization ofv difterent antenna. units in`r the array. v A Itis-often desiredtoprovide'an array of antennaunits inwhichenergy is distributed to providediierent current levels indifferentfantenna unitsi An example of such'an array. is thesecalledY binomial array whereinv the antenne.H elements are spacedfat regular 'intervalsv and are energized with currents decreasing from the een` ter outward-1y inaccordanee with the exponents ofI a` binomial4 expansion series; Inl the past, quite. complexl feeding arran-gements'fhavegenera ally lloeenfused in order'that the transmission line mayj leev yproperly adjusted: tofeed different currentsA to thefdiiferentA antenna units..

It. is anobject of m-y-invention to provide-an antenna array in` which'the'antenna units". are energized at dierent current levelstwithout'the necessity of.- providing variablefor. adjusted` iin pedance characteristicsinV thef-feederzlin. ccnnected tothe antenna It is:` afurtherobject roi. myV invention topro? vide an antennaarra'y` which the 'antennaielea ments themselves have selectively` diiI-erent yimpedancesf. tofcoritrolVr thel current levelfof energy supplied ther-etc.

This vinvention is' based upon the following: two impedance characteristics of radiators: First, whenak radiatorV substantially one electrical wave= length iszffed'at its center; the" input' impdance is; aiimction off the ratio ofzd'iameterte the lengtlr of:v the radiator: y As' .the diameter isf'iicreased: the` impedance reduced Heime',r by varying; thedianieterA of tli'e radiator' its impedancmaybecontrollech Secondly; When-ai halfi'wavlergtlf rfdldiat'rjl` is fed at its center, the impedaticciS-i's substantially independiit-ofdiameten of the radiator. However, if its length is made Vmore than a half wavelength, qua-rter Waveealch side of center, the impedance vwill become Y substantially higher.-

According to a feature of my-invention'a plurality of linear antenna elements forming ank array are coupled individually'to a transmission line-,=.said antenna elementsbeng given different impedance: characteristicsinf accordance; a desired ,cturent levelin eafclr-:of the respective antenna units. This may be accomplished by making the conductors of the antenna unit of different selected diameters or by making them of diierent selective lengths so that they will present the desired impedance. In the latter case it may be necessary to supply phasing eler'ati f-latva Applicatnm` December 16, 1942; ser'iaiio. maiis Fig. 351e a, stili furthe; modinatie p'f an aritenna-array constructed in accordance ivith' my intention-arie Y 4 Fig-l. 4-issti1lanojgher modicationof an array incorporating. the features- Qfjmy invention.-4 j) Turningrst nto-lige 1; Il l isatranslating-device` connected by *,rnearisfofv transmission line I I andibranch lines I-2` and=I3- t` ov-an antennauarray made up of elementsI Ill,v |55, I'B; ISA;l and Iligr. Each element-is4` made up. of two radiators substantially one half wavelength each. Successive elements are spacedy one hair wavelength apart. The translating uni-t Imay be eithena transmitter or'afreeeiver.-` In--brarichdiiesqlz and I3 are provided transpositionsf- I'I,` I@ and I9-, 201,A respectively? I Considering the' translating; unit I fas ad transgmitter; energy therefromvis fed over 1-ineI-Ijv di- 'rect'lyftov central element I #and overl branch lines t2 and=l3"to the vsuccessive units L51; Ida-nd; |55, I6A-,f.resp'ective1y;' Elements i5,-I-5A'and- I6:v H-A arc-v Iii-adeL successively smaller in` diameter than centralrelement I4 so that theypresentwsuccessively higher impedance across the feederl-ine. tccordingly;A thef currentI in they antennal uni-ts willbe successively lower as theouter ends er the array are approached:

If the antennafunitsare spaced apart one half olea wavelength atith'eopera-ting frequency and aref properly designed india-meter' tofhaye* the currents'tlierein'distributedefrom the center out- Ward-ly.: ini accordance* with the exponen-ts or a binomial expansion; then a2 normal' binomial array is provided.V By the? u'seof the" feeder systni`=i11us`trated=,-the feed-err line maybe madevto have substantially uniform impedancethiough'- oiitaridffthusftlie feedin'g-4 or the' antenna' elements select suitable diameters for the individua1 antenna units in order that the desired distribution of energy may be achieved.

In Fig. 2 is illustrated a six element antenna array fed by transmission line II and branch lines I2 and I3 similar to those shown in Fig. 1.

3 However, in this figure, no transpositions are provided between the successive antenna elements 2l, 22, 23 and 2lA, 22A and 23A. Accordingly, the antenna units are energized alternately in phase opposition if the spacing is maintained at a half wavelength. A transposition is provided at 2li4 in order that the two sides of the arrayl may maintainthe pattern of phase opposition.A It is clear that the system may, if desired, be fed in the same manner as the antenna elements of Fig. 1 if cophasal energization of the antenna units is desired.

In Fig. 3 is shown a further modification of my invention in which is provided feeder line il and branch lines l2 and I3 provided withtranjspo'si'-V tions 3) and 3l. To branched lines Si) and 3l are coupled antenna units 32, 33 and 32A, 33A,

-' respectively. In order to give different impedance characteristics to the separate antenna units, elements 33 and 33A arev madegreater in length thanelements 32, 32A which are made up of two quarter wavelength radiators each. Accordingly, these elements will present a higher impedance to the transmission line than 32 `and 32A which are made equal to a half wavelength at the operating frequency or an equivalent electrical length.

Since elements 33, 33A are not tuned to a half wavelength, they will tend to produce a phase shift in the energy supplied thereto. In order to take care of any such phase shift, individual phase correcting networks 34, 34A are provided. It is clear that with this type of antenna array the desired distribution of energy to the various units may be achieved without altering the irnpedance characteristics of the transmission line itself. Furthermore, this type of array may be extended in length in the same manner as the arrays shown in Figs l and 2, it being desirable in this case to provide the necessary phase shiftingunits for each of the antenna elements which departs from a half wavelength-equivalent length.

In Fig. 4 is shown still another modification in which an array of horizontal antenna elements lll, 2, IHA, 62A are arranged to befed from one end of a line 4i). The central antenna elements lll, IHA are made to have a lower impedance than the outer elements 42, 52A to provide the desired current distribution. Also, if the spacing between coupling points to line 4l] for the individual units is made equal to half a wavelength at the operating frequency and cophasal energization is desired, transpositions orother phase reversing means may be 'provided in the alternate individual feed linesllS, M, 43A, 44A, serving to supply energy tothe individualantenna units. If 180 phase of energization of the antenna units is desired so that the array will act as an end-re array instead of a broadside array, then the antenna units may be coupled to line lll without the phase reversing means.

It is clear that the end fed array of Fig. 4 may be` applied similarly to other arrays of the type shown in Figs. 1 to 3, inclusive, if desired. Also as many units as 'desired may be used in the array to provide the desired concentration of the radiation pattern.

Furthermore, the impedance adjustment of the individual units may be achieved in other ways than by changing of length or diameter as shown herein.

While I have described above the principles of my invention in connection with specific apparatus, and particular modications thereof, it is to be clearly understood that this description is made onlyby way of example and not as a limitation on the scope of my invention as set forth in the objects'of my invention and the accompanying claims.

' What is claimed is:

1. An antenna array in which the antenna elements forming said array are energized at different current levels comprising a feeder line, a plurality of antennaelements coupled to said feeder line at substantially half wave intervals, said antenna elements being made different in impedance in accordance with the desired current level in the respective elements.

2. An antenna array according to claim 1, wherein vsaid antenna elements are made ofv conductors-of differentselected dia Y eters togprovide the desired impedance characteristics.

3. An antenna arrayV according to claim 1 wherein said antenna elements,` are constructed with selectively different lengths to provide the desired impedance characteristics, further comprising phase adjusting means foradjusting the phase of current in the shorter of said elements to compensate for the phase shift caused by the difference in length of said elements.

4. An antenna array comprising a feeder line of substantially constant characteristic impedance, a plurality of antenna units coupled to said line at substantially 'half-'wave intervals at the operating frequency and means Vfor reversingfthe phase of energy in said feeder line between suc--YV cessively arranged antenna units, said antenna units being constructed to have selected different impedance characteristics tov provide a predetermined distribution of current therein.

5. vAn antenna array according to claim 4 wherein said antenna -units are vmade of conductors of different diameter tolprovidethe desired impedance characteristics.' i Y 7 6. An antenna array comprising a feederline having substantially constant characteristic impedance, a plurality of branch lines of substantially equal length coupled to said feeder line at substantially half wave intervals at the voperating frequency, a plurality of antenna unitsindividually coupled to said branch lines .and means for reversing the phase of energy of alternate ones of said branch lines, said antenna units being arranged in coaxial juxtaposition and con- .structed to have selected different impedance characteristic to provide a predetermined distribution of current thereinA and Yarranged to be fed from one end thereof.

ARMIG G. KANDOIAN.

REFERENCES CITED The following references are of file of this patent:

` UNITED STATES PATENTS record in the 

